The invention relates generally to toothbrushes, and, more particularly, to a toothbrush which provides effective removal of plaque and foreign matter from the lingual, or tongue, side of the teeth and from between teeth.
Toothbrushes of varying shapes and sizes are known for cleaning teeth and dental prosthesis. Typically, a toothbrush includes a rectangular or oval head, a handle, and a neck connecting the handle to the head. The head includes an array of bristles that are ultimately responsible for removing plaque and foreign matter from the teeth during brushing. The head (less the bristles), neck, and handle are typically formed as a unitary device through a molding process.
Most often, the head connects to the neck and the neck connects to the handle such that the resulting head, neck, and handle combination are in a relatively straight line along their longitudinal axes. However, in some other embodiments, such as those illustrated in U.S. Design Patent Nos. 44,997; 47,669; 73,245; 77,115; 175,894; 259,977; and 282,603, the neck and head are oriented perpendicular to each other in the shape of a xe2x80x9cT.xe2x80x9d The handle is typically straight, relatively long and rigid, but in some toothbrush designs the handle includes bends or angles either to make the handle more comfortable for a user to hold and/or to improve the toothbrush user""s ability to access hard-to-reach surfaces of the teeth.
Toothbrushes of the types described above are effective for cleaning most areas of the teeth or dental prosthesis, but they also have specific limitations. These limitations stem mainly from the fact that bristles, by their nature, clean most effectively when they extend substantially perpendicular to the surface being cleaned. Given the positioning and motion constraints that are present when using devices having long, straight, rigid handles within the confines of the human mouth, a user cannot readily position the bristles of prior art toothbrushes so that maximally effective cleaning can be realized over all areas of the teeth, dental work and gums, especially those areas that are on the lingual, or tongue, side of the teeth. These disadvantages have been overcome to some extent by various designs directed toward improving the maneuverability of toothbrush heads, such as making the head smaller, angling the brush handle and/or the head, providing a flexible joint in the handle or arranging bristles of varying lengths to form tufts having special contours intended to improve their penetration of irregularly shaped structures. Some examples of these improvements are described in U.S. Pat. Nos. 4,463,470; 4,800,608; 5,613,262; and 5,628,082.
However, improvements of the type noted above are not entirely sufficient to effectively enable cleaning of all areas of the teeth, particularly those areas on the lingual side of the teeth and between teeth. For example, typical prior art toothbrushes include an array of bristles extending from the head of the toothbrush and terminating with bristle tips which all lie in the same place. In contrast, the lingual side of the teeth defines a convex curvature. This convex curvature is particularly pronounced at the front, or anterior, portion of the mouth. Therefore, due to such geometric incompatibility, toothbrush heads cannot effectively clean all lingual side anterior tooth surfaces regardless of the configuration of the neck and head portions of the toothbrush. In addition, the straight nature of the necks of most toothbrushes makes maneuvering the toothbrush head difficult on the back (i.e., lingual) side of the teeth because the neck bumps into the teeth, deflecting the head of the brush away from proper contact with the lingual surface of the teeth.
To overcome the shortcomings of prior art toothbrush configurations, toothbrush users tend to engage the bristles with additional force on the lingual surfaces of the teeth in an attempt to more effectively clean the lingual tooth surfaces. However, brushing more forcefully does not necessarily result in cleaner teeth. Bristles clean most effectively when their tips engage the surface being cleaned using a force within a particular range depending on the stiffness of the bristles. If the force is not great enough, the bristle tips will not engage the surface being cleaned with sufficient pressure to do an effective a job of cleaning. On the other hand, if the force is too great, the bristles will bend or flatten so as to engage the surface being cleaned with their sides rather than their tips, also resulting in less than optimal cleaning.
Additionally, depending on the angle of engagement between the bristles and the teeth, and the force applied, flattening of some bristles may result in flattening of other bristles due to the proximity of all the bristles on the toothbrush head. For example, when one brushes the lingual side of his or her posterior, or back teeth, he or she typically angles the toothbrush in an attempt to avoid the anterior teeth and almost invariably engages the lingual tooth surfaces first with the tips of the bristles at the front end of the toothbrush head opposite the handle. As the force applied to the bristles is increased, the front bristles bend in a longitudinal direction toward the rear of the toothbrush head contacting neighboring bristles and causing the neighboring bristles to likewise bend rearwardly. This domino effect continues, affecting all the bristles in such a manner that the bristles engage tooth surfaces on their sides instead of at their tips. Such side engagement repeats as the person moves the toothbrush head back-and-forth in his or her mouth. As noted above, engaging the tooth surfaces with the sides of the bristles results in less than optimal cleaning.
The above limitations of prior art toothbrushes also extend to cleaning between teeth. Bristles clean between teeth most effectively when their tips project between the teeth. However, due to the flat shape of many toothbrush heads and the geometry of the toothbrush neck, cleaning between teeth, particularly from the lingual side of the teeth, is difficult. Consequently, toothbrush users typically apply excessive force to the bristles in an attempt to force the tips of the bristles into the spaces between the teeth. Application of excessive force typically results in the tips of the bristles deflecting away from the surface intended to be cleaned and less efficient cleaning occurs.
It is therefore among the objectives of this invention to provide a toothbrush which facilitates effective cleaning of the lingual side of the teeth and between teeth, and which permits toothbrush users to have enough confidence when brushing to apply only the appropriate amount of force related to the stiffness of the bristles of their toothbrushes.
In one presently preferred embodiment, a toothbrush is provided which includes a head whose bottom (i.e., bristle-bearing) surface and preferably its top (i.e., non-bristle bearing) surface have a convex curvature that complements the geometric shape of a typical human mouth on the lingual side of the teeth. Such a convex curvature, which may be either a smooth continuous curve or a piecewise, approximation formed by the angular intersection of two or more planes, approximates the geometric shape of the mouth on the lingual side of the teeth.
According to another aspect of the present invention, the toothbrush includes a bristle arrangement in which the bristles project from the bristle-bearing surface of the head by distances appropriate to cause the tips of the bristles to form a generally convex profile that substantially complements the curvature of mouth on the lingual side of the teeth. Thus, the present invention seeks to accommodate the general geometric shape of the mouth on the lingual side of the teeth with a curvature of the bristle-bearing surface of the head, an arrangement of the bristles, or both that generally complement the mouth""s shape. By effectively matching the geometric shape of the mouth on the lingual side of the teeth with the shape of the bristle-bearing surface of the head and/or the profile of the bristles, the present invention improves the likelihood that a substantial quantity of bristles will continuously engage the lingual side tooth surfaces at an appropriate angle and force, thereby resulting in improved lingual side cleaning efficacy.
According to yet another aspect of the present invention, the toothbrush further includes a neck having a concave curvature with respect to the brushing surface of the teeth. Such a concave curvature may be either a smooth continuous curve or a segmented approximation formed by the angular intersection of two or more planes. With a concave curvature in the neck, the toothbrush user can more easily, naturally, and reliably maneuver the toothbrush head and bristles on the tongue side of the teeth without interference from the teeth themselves, in contrast to the interference that may be encountered when using straight-necked toothbrushes.
According to a further aspect of the present invention, a toothbrush is provided with a neck and a head oriented in a T-configuration to facilitate easy access to the lingual side of the anterior teeth without requiring the toothbrush user to perform substantial arm and wrist movements to maneuver the toothbrush head behind the anterior teeth. That is, the neck is coupled to a central area of the head such that the longitudinal axis of the head is substantially perpendicular to the longitudinal axis of the neck. In a preferred aspect of the T-configuration toothbrush, the neck is coupled to the head at an angle directed away from the brushing surface. Coupling the head and neck together in this manner effectively results in a slight tilting of the head in an upward direction to accommodate the curvature of either the palate or the bottom part of the mouth, below the tongue.
According to still a further aspect of the present invention, the toothbrush further includes a handle coupled to the neck, wherein the handle preferably includes one or more bends or angles to aid gripping of the toothbrush and maneuvering of the toothbrush in the mouth. Such bending or angling of the handle may be in one plane or in multiple planes.
In another embodiment of this invention, the bristle bearing surface of the head section includes a first end, a second end connected to the neck of the toothbrush, opposed sides extending between the ends and a central bristle mounting area located between the opposed sides but spaced from each of the first and second ends where an array of bundles of bristles are mounted to the head. A first group of bristle supports extend from the first end to the central bristle mounting area, and a second group of bristle supports are positioned on the head between the second end and central bristle mounting area. Preferably, each of the first and second groups of bristle supports has a length measured in the longitudinal direction, e.g. in a direction between the ends, which is in the range of about xc2xc to xc2xd of the length of the bristles within the central bristle mounting area. The purpose of the bristle supports is to resist deflection of the bristles within the central bristle mounting area in the longitudinal direction upon contact with the teeth, and particularly the lingual side of the teeth. This assists in maintaining the tips of the bristles in contact with the surfaces of the teeth for improved cleaning, rather than allowing the bristles to bend so that their sides contact the teeth.